function timeFinish(i)
{
var t=setTimeout("alertMsg()",i);
}
function alertMsg()
{
alert("Time of Experiment is Finish");
}

var c=0;
var t;
var timer_is_on=0;

function timedCount()
{
document.getElementById('txt').value=c;
c=c+1;
t=setTimeout("timedCount()",1000);
}

function doTimer()
{
if (!timer_is_on)
  {
  timer_is_on=1;
  timedCount();
  }
}